1. Technical Field of the Invention
The present invention relates to a valve assembly for controlling the flow of liquids or gases or fluid particulate matter within sealed conduit systems, such systems being used for example, without limitation, in the food and drink industry, fire fighting, aviation, aeronautical, space, gas and oil industries, health care, pharmaceutical industry, utility services and process engineering industries.
Small low-pressure valves are usually made of brass, aluminium or plastics, whilst larger valves are typically made of brass and other alloys. Alloys, such as stainless steel, may be required if the controlled fluid is corrosive. Valves may be actuated manually, or mechanically through a servomechanism, or magnetically or pneumatically by the flow of the controlled fluid. The present invention relates to a valve assembly that is actuated magnetically.
2. Description of the Prior Art
It is known from the prior art to provide valves and to provide pulsed electrical current so as to actuate the valve. However the problems associated with conventional types of solenoid valve assemblies is that the coils can generate a great amount of thermal energy. Thus, conventional solenoid valves are of limited use with cryogenic fluids and can cause hygiene problems with their use in the food and drinks industry. Moreover, these valves require a return spring and a plunger mechanism. The spring/plunger being capable of closing the valve against a direction of line pressure when the power to the coil is shut off. Additionally conventional solenoid valves require a seal to separate the internal line pressure one side of the spring/plunger from atmospheric pressure. These seals can wear and/or rupture thus allowing fluid leakage, which can be both hazardous and expensive.
Most large diameter valves installed in industrial systems require substantial electrical installations and/or compressed air facilities to control the flow of liquids or gases. Compressed air facilities in themselves require electrical installation systems and so the cost and difficulty of installing such large diameter solenoid valves can be immense.
A yet further problem associated with conventional solenoid valves is that they are expensive to maintain in that they need to remain permanently energised. So, for example, a solenoid valve that is only operated on a very occasional basis, perhaps once or twice per year, will have to remain fully energised for the entire period. This can be extremely expensive in wattage.
A valve assembly that is easy to install, cost effective to maintain and comprising fewer seals and moving parts would offer an immediate advantage to many industries and would have wide application.
According to a the present invention there is provided a valve comprising a valve body and, located therein, a valve member movable between a first position in which the valve is in a first operational mode and a second position in which the valve is in a second operational mode, the valve member including a rare earth magnet which, when the valve member is in either one of said positions, causes the valve member to be magnetically biased against movement towards the other of said positions, the valve being provided with means for generating a magnetic field sufficient to overcome the magnetic bias in the first or second position so as to cause said valve member to move to the other of said positions.
Preferably said rare earth magnet is composed of at least one of the elements selected from the group consisting of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, yttrium and thorium.
Preferably said rare earth magnet is composed of more than one rare earth material, and more preferably said rare earth magnet can be permanently magnetised with its magnetic axis aligned in any selected direction.
Preferably the magnet includes at least one element other than a earth metal. For example iron, boron and/or cobalt, an examples of such compositions are BREMAG (NeFeB) and ANISOTROPIC BREMAG (SmCo). The rare earth magnet is almost impossible to demagnetise using a conventional coil assembly and short periods of opposing magnetic force which will occur when the valve is opened or closed.
Preferably said rare earth magnet is a disc having substantially parallel faces and more preferably said disc is magnetised with its magnetic axis aligned perpendicular to said faces.
Preferably said rare earth magnet is enclosed within the valve body.
Preferably the housing is provided with a seat for the valve member, the seat being provided with a plurality of rare earth magnets arranged in a circular configuration about the valve member. Preferably the rare earth magnets are evenly spaced apart.
Preferably the valve is substantially circular in plan and is of more than 2 inches (5 cm) diameter.
Preferably the valve includes a magnetic coil within which a magnetic field is generated by means of applied electrical current ideally by direct current.
Preferably said coil is composed of iron or iron ferrite.
Preferably power is supplied by a rechargeable battery, such a battery being provided on a vehicle/truck or the like, ideally said battery can operate a relatively large valve thereby eliminating the need for a substantial power supply, moreover the battery can be replenished with a trickle charger using either local power, for example from a telephone supply, or solar power or wind generated power.
Thus, it will be understood that the rare earth magnet oscillates between the two said operational modes i.e. open and closed positions by reversing the direct current excitation voltage across the coil. Reversing the current acts to either attract or repel the rare earth magnet disc between the open and closed positions of the valve. It is only necessary to energise the coil for a short period of time, ideally in the region of 0.25-10 seconds, this is because when the rare earth magnet disc is in an open position it is held in position by its own magnetic attraction to the iron or iron ferrite material employed in the coil construction. This feature offers significant advantage over the prior art.
Preferably said valve comprises a valve seat which is composed of magnetic material.
In a closed position, the rare earth magnet disc is held in position by both its magnetic attraction to magnetic materials in and around a valve seat in addition to the differential pressure across the valve. The time taken to switch the valve between the two operational modes is more rapid than a motorised or pneumatic valve, thus it is envisaged that the valve of the present application has applications in the fire prevention industry and other safety situations.
Preferably said valve comprises a plurality of static seals mounted on one or both of the valve member and valve body to provide sealing therebetween. Preferably, at least one of said static seals is positioned between the rare earth magnet disc and the valve seat and another of said static seals is positioned on an inner surface of an outlet port of the valve.
It is of note that the valve of the present invention does not require any form of seal between the coil and the valve seat. As a consequence, of this there is no possibility of leakage from the valve interior to the surrounding environment, making the present invention particularly suitable as a control valve in conduits/pipes containing flowing explosive material and/or hazardous material and/or material that needs to be pathogen free.